Error in tensor size

Traceback (most recent call last):
  File "project.py", line 234, in <module>
    output = torch.cat((output,prediction))
RuntimeError: invalid argument 0: Sizes of tensors must match except in dimension 0. Got 8 and 86 in dimension 1 at c:\a\w\1\s\windows\pytorch\aten\src\thc\generic/THCTensorMath.cu:83

All the images in the folder are of size 1280 x 720

Code:

from __future__ import division
import time
import torch 
import torch.nn as nn
from torch.autograd import Variable
import numpy as np
import cv2 
from util import *
import argparse
import os 
import os.path as osp
from darknet import Darknet
from preprocess import prep_image, inp_to_image
import pandas as pd
import random 
import pickle as pkl
import itertools

class test_net(nn.Module):
    def __init__(self, num_layers, input_size):
        super(test_net, self).__init__()
        self.num_layers= num_layers
        self.linear_1 = nn.Linear(input_size, 5)
        self.middle = nn.ModuleList([nn.Linear(5,5) for x in range(num_layers)])
        self.output = nn.Linear(5,2)
    
    def forward(self, x):
        x = x.view(-1)
        fwd = nn.Sequential(self.linear_1, *self.middle, self.output)
        return fwd(x)
        
def get_test_input(input_dim, CUDA):
    img = cv2.imread("dog-cycle-car.png")
    img = cv2.resize(img, (input_dim, input_dim)) 
    img_ =  img[:,:,::-1].transpose((2,0,1))
    img_ = img_[np.newaxis,:,:,:]/255.0
    img_ = torch.from_numpy(img_).float()
    img_ = Variable(img_)
    
    if CUDA:
        img_ = img_.cuda()
    num_classes
    return img_



def arg_parse():
    """
    Parse arguements to the detect module
    
    """
    
    
    parser = argparse.ArgumentParser(description='YOLO v3 Detection Module')
   
    parser.add_argument("--images", dest = 'images', help = 
                        "Image / Directory containing images to perform detection upon",
                        default = "imgs", type = str)
    parser.add_argument("--det", dest = 'det', help = 
                        "Image / Directory to store detections to",
                        default = "det", type = str)
    parser.add_argument("--bs", dest = "bs", help = "Batch size", default = 1)
    parser.add_argument("--confidence", dest = "confidence", help = "Object Confidence to filter predictions", default = 0.5)
    parser.add_argument("--nms_thresh", dest = "nms_thresh", help = "NMS Threshhold", default = 0.4)
    parser.add_argument("--cfg", dest = 'cfgfile', help = 
                        "Config file",
                        default = "cfg/yolov3.cfg", type = str)
    parser.add_argument("--weights", dest = 'weightsfile', help = 
                        "weightsfile",
                        default = "yolov3.weights", type = str)
    parser.add_argument("--reso", dest = 'reso', help = 
                        "Input resolution of the network. Increase to increase accuracy. Decrease to increase speed",
                        default = "416", type = str)
    parser.add_argument("--scales", dest = "scales", help = "Scales to use for detection",
                        default = "1,2,3", type = str)
    
    return parser.parse_args()

if __name__ ==  '__main__':
    args = arg_parse()
    
    scales = args.scales
    
    
#        scales = [int(x) for x in scales.split(',')]
#        
#        
#        
#        args.reso = int(args.reso)
#        
#        num_boxes = [args.reso//32, args.reso//16, args.reso//8]    
#        scale_indices = [3*(x**2) for x in num_boxes]
#        scale_indices = list(itertools.accumulate(scale_indices, lambda x,y : x+y))
#    
#        
#        li = []
#        i = 0
#        for scale in scale_indices:        
#            li.extend(list(range(i, scale))) 
#            i = scale
#        
#        scale_indices = li

    images = "D:\\project\\splitvideo\\data"
    batch_size = int(args.bs)
    confidence = float(args.confidence)
    nms_thesh = float(args.nms_thresh)
    start = 0

    CUDA = torch.cuda.is_available()

    num_classes = 80
    classes = load_classes('data/coco.names') 

    #Set up the neural network
    print("Loading network.....")
    model = Darknet(args.cfgfile)
    model.load_weights(args.weightsfile)
    print("Network successfully loaded")
    
    model.net_info["height"] = args.reso
    inp_dim = int(model.net_info["height"])
    assert inp_dim % 32 == 0 
    assert inp_dim > 32

    #If there's a GPU availible, put the model on GPU
    if CUDA:
        model.cuda()
    
    
    #Set the model in evaluation mode
    model.eval()
    
    read_dir = time.time()
    #Detection phase
    try:
        imlist = [osp.join(osp.realpath('.'), images, img) for img in os.listdir(images) if os.path.splitext(img)[1] == '.png' or os.path.splitext(img)[1] =='.jpeg' or os.path.splitext(img)[1] =='.jpg']
    except NotADirectoryError:
        imlist = []
        imlist.append(osp.join(osp.realpath('.'), images))
    except FileNotFoundError:
        print ("No file or directory with the name {}".format(images))
        exit()
        
    if not os.path.exists(args.det):
        os.makedirs(args.det)
        
    load_batch = time.time()
    
    batches = list(map(prep_image, imlist, [inp_dim for x in range(len(imlist))]))
    im_batches = [x[0] for x in batches]
    orig_ims = [x[1] for x in batches]
    im_dim_list = [x[2] for x in batches]
    im_dim_list = torch.FloatTensor(im_dim_list).repeat(1,2)
    
    
    
    if CUDA:
        im_dim_list = im_dim_list.cuda()
    
    leftover = 0
    
    if (len(im_dim_list) % batch_size):
        leftover = 1
        
        
    if batch_size != 1:
        num_batches = len(imlist) // batch_size + leftover            
        im_batches = [torch.cat((im_batches[i*batch_size : min((i +  1)*batch_size,
                            len(im_batches))]))  for i in range(num_batches)]        


    i = 0
    

    write = False
    model(get_test_input(inp_dim, CUDA), CUDA)
    
    start_det_loop = time.time()
    
    objs = {}
    
    
    
    for batch in im_batches:
        #load the image 
        start = time.time()
        if CUDA:
            batch = batch.cuda()
        

        #Apply offsets to the result predictions
        #Tranform the predictions as described in the YOLO paper
        #flatten the prediction vector 
        # B x (bbox cord x no. of anchors) x grid_w x grid_h --> B x bbox x (all the boxes) 
        # Put every proposed box as a row.
        with torch.no_grad():
            prediction = model(Variable(batch), CUDA)
        
#        prediction = prediction[:,scale_indices]

        
        #get the boxes with object confidence > threshold
        #Convert the cordinates to absolute coordinates
        #perform NMS on these boxes, and save the results 
        #I could have done NMS and saving seperately to have a better abstraction
        #But both these operations require looping, hence 
        #clubbing these ops in one loop instead of two. 
        #loops are slower than vectorised operations. 
        
        prediction = write_results(prediction, confidence, num_classes, nms = True, nms_conf = nms_thesh)
        
        
        if type(prediction) == int:
            i += 1
            continue

        end = time.time()
        
                    
#        print(end - start)

            

        prediction[:,0] += i*batch_size
        
    
            
          
        if not write:
            output = prediction
            write = 1
        else:
            output = torch.cat((output,prediction))
            
        
        

        for im_num, image in enumerate(imlist[i*batch_size: min((i +  1)*batch_size, len(imlist))]):
            im_id = i*batch_size + im_num
            objs = [classes[int(x[-1])] for x in output if int(x[0]) == im_id]
            print("{0:20s} predicted in {1:6.3f} seconds".format(image.split("/")[-1], (end - start)/batch_size))
            print("{0:20s} {1:s}".format("Objects Detected:", " ".join(objs)))
            print("----------------------------------------------------------")
        i += 1

        
        if CUDA:
            torch.cuda.synchronize()
    
    try:
        output
    except NameError:
        print("No detections were made")
        exit()
        
    im_dim_list = torch.index_select(im_dim_list, 0, output[:,0].long())
    
    scaling_factor = torch.min(inp_dim/im_dim_list,1)[0].view(-1,1)
    
    
    output[:,[1,3]] -= (inp_dim - scaling_factor*im_dim_list[:,0].view(-1,1))/2
    output[:,[2,4]] -= (inp_dim - scaling_factor*im_dim_list[:,1].view(-1,1))/2
    
    
    
    output[:,1:5] /= scaling_factor
    
    for i in range(output.shape[0]):
        output[i, [1,3]] = torch.clamp(output[i, [1,3]], 0.0, im_dim_list[i,0])
        output[i, [2,4]] = torch.clamp(output[i, [2,4]], 0.0, im_dim_list[i,1])
        
        
    output_recast = time.time()
    
    
    class_load = time.time()

    colors = pkl.load(open("pallete", "rb"))
    
    
    draw = time.time()


    def write(x, batches, results):
        c1 = tuple(x[1:3].int())
        c2 = tuple(x[3:5].int())
        img = results[int(x[0])]
        cls = int(x[-1])
        label = "{0}".format(classes[cls])
        color = random.choice(colors)
        cv2.rectangle(img, c1, c2,color, 1)
        t_size = cv2.getTextSize(label, cv2.FONT_HERSHEY_PLAIN, 1 , 1)[0]
        c2 = c1[0] + t_size[0] + 3, c1[1] + t_size[1] + 4
        cv2.rectangle(img, c1, c2,color, -1)
        cv2.putText(img, label, (c1[0], c1[1] + t_size[1] + 4), cv2.FONT_HERSHEY_PLAIN, 1, [225,255,255], 1)
        return img
    
            
    list(map(lambda x: write(x, im_batches, orig_ims), output))
      
    det_names = pd.Series(imlist).apply(lambda x: "{}/det_{}".format(args.det,x.split("/")[-1]))
    
    list(map(cv2.imwrite, det_names, orig_ims))
    
    end = time.time()
    
    print()
    print("SUMMARY")
    print("----------------------------------------------------------")
    print("{:25s}: {}".format("Task", "Time Taken (in seconds)"))
    print()
    print("{:25s}: {:2.3f}".format("Reading addresses", load_batch - read_dir))
    print("{:25s}: {:2.3f}".format("Loading batch", start_det_loop - load_batch))
    print("{:25s}: {:2.3f}".format("Detection (" + str(len(imlist)) +  " images)", output_recast - start_det_loop))
    print("{:25s}: {:2.3f}".format("Output Processing", class_load - output_recast))
    print("{:25s}: {:2.3f}".format("Drawing Boxes", end - draw))
    print("{:25s}: {:2.3f}".format("Average time_per_img", (end - load_batch)/len(imlist)))
    print("----------------------------------------------------------")

    
    torch.cuda.empty_cache()

Print the shapes of tensors ‘output’ and ‘prediction’ right before that line, and then keep inserting print statements in the preceding code until you see where one of them gets the incorrect shape.

print(output.size(), prediction.size())

Thank you so much. I will try it

Just a question. All the images in the batch are of same size.
The code generates output for some files and error for the rest.
How’s that possible if all files have identical properties ?